Instructions
Place whole peppercorns in a zip bag and crush with a rolling pin or mortar and pestle into coarse chunks, not fine powder.
Pat steaks dry. Season with salt, then press cracked peppercorns firmly into both surfaces. Rest at room temperature 30–40 minutes.
Heat cast-iron skillet over medium-high. Add olive oil and butter. When butter foams, lay steaks down gently.
Sear 3–4 minutes per side for medium-rare (adjust for preference). Do not move steaks while crust forms.
Transfer steaks to a warm plate, tent with foil, and rest while making the sauce.
In the same skillet, reduce heat slightly. Add minced shallots and saute 30 seconds, scraping up the browned bits.
Pour in cognac. Tilt pan toward the flame to flambe, or use a long lighter. A burst of blue flame will appear briefly, then die. Stir to deglaze.
Add beef stock and let reduce 1–2 minutes. Pour in heavy cream and Dijon mustard, stirring constantly. Simmer 3–5 minutes until sauce coats the back of a spoon.
Whisk in 1 tbsp butter for a glossy finish. Taste and adjust seasoning.
Return steaks and any resting juices to the pan. Spoon sauce over the top and simmer gently 30 seconds. Plate immediately with sauce spooned generously over each steak.